Three's Company: A Trio of Americans Wins the Nobel Prize

Three Americans have been awarded the Nobel Prize in physiology or medicine for their work on telomeres, the tips at the ends of chromosomes, and telomerase, the enzyme involved in maintaining telomeres during DNA replication. Elizabeth Blackburn (University of California, San Francisco), Carol Greider (John Hopkins University School of Medicine), and Jack Szostak (Harvard Medical School and Massachusetts General Hospital) revealed the key to understanding how chromosomes stay intact over time (pictured from left to right).

Here's the short version of why their work is important. Typically, chromosomes are replicated before a cell divides, and then they are redistributed into new cells. However, the normal process of replication before cell division tends to shorten the tips of chromosomes (due to physical constraints on capturing all the entire DNA sequence in these tips). In fact, over multiple cell divisions, chromosomes can degrade over time and these tips can become shorter. Despite this observation, cells with the enzyme telomerase don't show this degradation because telomerase compensates for this shortening phenomenon by specificlaly facilitating replication at chromosome tips. This very specific action by the telomerase enzyme works by extending telomere DNA, and allowing DNA polymerases to copy the entire chromosome via a support structure at the telomeres. Also, the genetic makeup of telomeres themselves enables them to draw in proteins that form a "protective cap" which shields the delicate tips of chromosomes from decay over time. But this doesnt occur in every cell.

So why is this tip preservation important? Scientists think that knowledge about telomeres will help us all understand how cells age, and aging in general. This is because chromosomal shortening is associated with aging cells and the aging tissues they make up, so further studies into telomere shortening processes may hold the key to knowing how and why our cells and our bodies mature over long periods of time. Cancer cells also a kind of opposite to aging cells because of the fact that they divide infinitely. In fact, cancer cells have greater quantities of telomerase, more than normal cells — which might help explain their seemingly immortal state. This doesn't explain cancer, but it definitely gives scientists a clue about what goes wrong inside cancerous cells.

The discovery of telomeres and telomerase by Blackburn, Greider, and Szostak has opened up and sparked an enormous field of research into human aging and diseases like cancer, and even stem cell therapies. The major reason is that examination of abnormalities in telomerase function leading to aging or degradation of tissue, like those seen in limited cell division and cell growth, can help in the design of new treatments that aim to recover skin, lung, and bone marrow tissue. Conversely, it's possible to design therapeutics to reduce telomerase, which can aid in the treatment of cancer.

This week the Nobel Foundation has recognized the relevance of these scientists' work. You can check out some more details here:

Nobel Foundation. The Nobel Prize in Physiology or Medicine 2009. 5 October 2009.